The invention relates to a unique way of using an oil separator circuit to combine its function with a hot gas bypass circuit.
Hot gas bypass circuits are widely used for controlling the cooling capacity of refrigeration systems. The essence of the method is to redirect part of the compressor discharge flow as it passes through an oil separator back to the suction side to effectively reduce the evaporator capacity, without having to modulate the compressor flow.
Partial separation of oil from the oil gas mixture which leaves the compressor discharge is frequently used to minimize refrigeration system oil circulation rates. The oil separated from the discharge gas in the oil separator is directed back to the compressor suction side, while refrigerant gas with a minimal amount of oil is allowed to proceed toward the condenser. This ensures reliable compressor operation as a sufficient amount of lubricant is maintained in the compressor at all times. At the same time, the amount of oil dispersed in the system and accumulated on heat transfer surfaces of heat exchangers (such as the evaporator, condenser, economizer and suction-liquid heat exchanger, etc.) is reduced. Consequently, the overall system performance is improved.
Both hot gas bypass and oil separation circuits are often required elements of a refrigeration system. In the prior art systems, each of these circuits required separate sets of valves, connecting piping, support structure, power wiring and control hardware. Addition of the required components increased the overall system cost, complicated the geometry, and impacted serviceability. Further, the additional piping created more opportunities for refrigerant leaks. All of the above factors complicated refrigeration system design in the highly competitive and reliability sensitive air conditioning and refrigeration markets.
It is a goal of this invention to achieve a hot gas bypass operation without the necessity of including additional flow lines or valves into the refrigerant system, where an oil separator has already been installed to separate and return oil to the compressor housing.